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Showing 1 to 16 of 16 for “"Spherules"”.
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Trace Element Geochemistry of Compositionally Layered Impact Spherules
Impact spherules are sand-sized spherical particles that have been interpreted to have formed by the cooling, crystallization, and quenching of melt droplets condensed from vapor plumes that are created during large meteor impacts. Spherules may be deposited globally as unique marker beds, such as …
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Black magnetic spherules from the glacial and sea ice of Fletcher's Ice Island (T-3)
<p>Black magnetic spherules are particles which can be derived by ablationary processes from cosmic sources. Spherules from both the glacial ice and sea ice of Fletcher's Ice Island (T-3) were studied to determine their size distribution, sedimentation rates, and other parameters. The results were …
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Microanalysis of impactors of the earth and impact products from the moon : the origin and evolution of micrometeorites, and tracking bombardment history through chemical and radioisotopic memories of lunar impact spherules
… micrometeorites and lunar impact spherules. The purpose of the first project was primarily method development, although a study of micrometeorite petrography, chemistry, atmospheric alteration, and potential origin ensued. A classification system was developed with a focus on …
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Microanalysis of impactors of the earth and impact products from the moon : the origin and evolution of micrometeorites, and tracking bombardment history through chemical and radioisotopic memories of lunar impact spherules
… micrometeorites and lunar impact spherules. The purpose of the first project was primarily method development, although a study of micrometeorite petrography, chemistry, atmospheric alteration, and potential origin ensued. A classification system was developed with a focus on …
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The Formation of Distal Impact Ejecta
… or fireball. In this model molten droplets or spherules condense from the vapor. We model the expanding vapor plume using a one dimensional Lagrangian hydrocode. The condensation of droplets is treated by directly coupling the equations for homogeneous nucleation and growth with our hydrocode. …
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An investigation into the physiology of urate pellet excretion by Parcoblatta fulvescens (Saussure and Zehntner) (Dictyoptera: Blattellidae)
… nitrogen reserves among individuals. Urate spherules were enzymatically and histochemically identified in the middle and proximal regions of the Malpighian tubules of <i>P. fulvescens</i>, <i>Shawella couloniana</i> and <i>Symploce hospes</i>. These spherules are discharged into the hindgut …
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Ηλεκτρονική μικροσκοπία της ανθρώπινης επίφυσης (κωναρίου): Συγκριτική μελέτη στις διάφορες ηλικίες
… which are unique to the pineal (e.g. synaptic spherules, microtubular sheaves) or characteristic for the pineocyte and a few other cell types (e.g. synaptic ribbons). These organelles were not described in the human embryonic pineal. The function of microtubular sheaves is not known but it is …
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Applied Geochemistry, Geochronology and Biostratigraphy: Case Studies from the 38th Parallel Structures in Missouri and Orange Basin, Offshore Western South Africa
… organic matter) and radiometric dating of impact spherules were used to constrain age and a relationship between these enigmatic structures and infer their paleoenvironmental conditions. Novel melting damages, unique to impact, were documented in the palynomorphs in all the three structures. Early …
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Paleomagnetism of Lonar impact glass
… Based on the NRM/sIRM ratios of the splash-form spherules the glasses slightly underestimate the intensity of the field in which they cooled. This underestimate is in part possibly due to the effects of rotation during cooling. Their unique motional remanent magnetization is quite fascinating, …
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The ultrastructure of a marine luminous bacterium
… within the cell wall. Small cytoplasmic spherules which arise from the cytoplasmic membrane were also seen to occur. The cell walls which were three-layered and typical of Gram-negative bacteria often had blebs on the surface. The cytoplasmic membrane, typical of a 7.5 nm unit biological …
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Characterization of an Amphipathic Alpha-Helix in the Membrane Targeting and Viral Genome Replication of Brome Mosaic Virus
… to establish replication complexes termed spherules. 1a has a strong affinity towards the perinuclear ER membrane, however, the structural features in 1a that dictate its membrane associations and thereby membrane remodeling activities are unclear. This study examined the possible role of …
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Formation conditions of plagioclase-bearing type I chondrules in CO chondrites : a study of natural samples and experimental analogs
… is chondrules, which are small igneous spherules that formed from the melting of precursor dust ball assemblages during very short, high-temperature events in the solar nebula. Chondrules typically contain olivine and pyroxene, a glassy mesostasis, Fe-Ni metal, and sulfides. Type I …
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The Geobiology of the Paleoproterozoic Belcher Group, Nunavut, Canada
… XPS show that organic carbon is present in the spherules from the Kipalu Formation, which suggests microbiota could have facilitated the deposition of the granular iron formation. Pseudofossils were discovered during the re-examination of McLeary Formation samples, which show that abiotic …
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Benthic foraminiferal change and depositional history across the Cretaceous – Paleogene (K/Pg) boundary in the Brazos River area, Texas
… ‘Event Bed’, containing reworked impact spherules at its base, is shown to infill troughs on this irregular surface. The same features were recorded in tributary creeks, with all previous descriptions of these locations clearly failing to recognise the various sedimentary relationships. …
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Composition and fabric of the Kupferschiefer, Sangerhausen Basin, Germany and a comparison to the Kupferschiefer in the Lubin Mining District, Poland
… mineralization, in the form of disseminated spherules, blebs, aggregates, framboids, and bedding-parallel and -perpendicular veins, is observed in both locations on macro- and microscopic scales. The most abundant sulfide in mineralized samples from both locations is chalcocite, followed by …